In high speed submicron lithography, an electron beam is focused and imaged toward its target. The target is a sensitive material which is exposed by the beam to permit different states of treatment of the substrate underlying the sensitive material. Usually the material is photosensitive which includes sensitivity to electron and/or ion beams. The beam is deflected to form a writing path on the target to produce an exposure pattern thereon. There are writing requirements which necessitate that the beam be blanked during certain parts of the deflection, in order to write separate patterns on the substrate. This invention is directed to high speed blanking which does not slow down writing or misdirect the beam during writing.
There are two classes of electron beam equipment. In the first class, a small, high brightness electron source is focused, deflected and demagnified onto the target to produce a writing spot. This is considered to be a Gaussian beam because of the angular distribution of electrons from the high brightness source. The second class of electron beam equipment uses a source which floods an aperture to produce a specific beam shape. This flooded aperture is then focused, deflected and demagnified onto the target. In either case, a blanking deflector is positioned adjacent the beam to deflect the beam away from a blanking aperture sufficiently that little beam energy passes onto the target. The blanking deflector and blanking aperture thus achieve cutoff of the beam during non-writing portions of the operation.